The present invention relates to an image forming apparatus such as an electrostatic recording apparatus or an electrophotographic apparatus and to a fixing device used in the image forming apparatus.
In an image requiring high quality such as a full-color image, the roughness of the image was a problem to be solved in the past. The roughness is derived from the nonuniformity of the dots forming the image. Particularly, the nonuniform melting of the developing agent in the fixing step under a thermal pressure and the collapse of the dots caused by the pressure were considered to be the main causes of the nonuniformity of the dots. Such being the situation, it has been known in the art to suppress the nonuniformity of the dots in the fixing step by using a fixing roller made of rubber having a low hardness. However, the fixing roller made of rubber having a low hardness has a short life, and so increases the printing cost.
On the other hand, a method is employed using a roller covered with a fluorine-containing resin such as perfluoroalkoxy resin (PFA) as a means for prolonging the life of the fixing roller. However, the roller of this type has an excessively high hardness so as to bring about the nonuniformity of the dots in the fixing step so as to further promote the roughness. Also, where the roller is covered with a fluorine-containing resin having a low hardness, the covering surface layer is wrinkled in the manufacturing process of the roller so as to cause a nonuniform fixing of the printed image.
An object of the present invention, which has been achieved in view of the situation described above, is to obtain easily and at a low cost an image of a high quality free from roughness.
According to a first aspect of the present invention, there is provided an image forming apparatus, comprising:
an image carrier;
a developing device to form a developing agent image on the image carrier by using a developing agent;
a transfer device to transfer the developing agent image onto a recording surface of a recording material; and
a fixing device to fix the transferred developing agent image onto the recording surface, the fixing device including a fixing belt movably supported by a rotatable heating member and a rotatable support member equipped with a surface elastic layer having a hardness not higher than 40xc2x0, and a pressurizing mechanism arranged to face the support member with the fixing belt interposed therebetween and equipped with a pressurizing member movable in synchronism with the fixing belt.
According to a second aspect of the present invention, there is provided an image forming apparatus, comprising:
a first image carrier;
a first developing device to form a first developing agent image on the first image carrier by using a first developing agent;
a second image carrier;
a second developing device to form a second developing agent image on the second image carrier;
a transfer device to transfer the second developing agent image onto a recording surface of a recording material after transfer of the first developing agent image onto the recording surface of the recording material; and
a fixing device to fix the transferred developing agent image onto the recording surface, the fixing device including a fixing belt movably supported by a rotatable heating member and a rotatable support member equipped with a surface elastic layer having a hardness not higher than 40xc2x0, and a pressurizing mechanism arranged to face the support member with the fixing belt interposed therebetween and equipped with a pressurizing member movable in synchronism with the fixing belt.
According to a third aspect of the present invention, there is provided a method for forming an image, comprising:
developing a latent image to form a developing agent image on an image carrier by using a developing agent;
transferring the developing agent image onto a recording surface of a recording material to form a transferred image; and
fixing the transferred image to the recording surface by introducing a recording material having the transferred image into a fixing device including a rotatable heating member, a fixing belt movably supported by a rotatable support member equipped with a surface elastic layer having a hardness not higher than 40xc2x0, and a pressurizing mechanism arranged to face the support member with the fixing belt interposed therebetween and equipped with a pressurizing member movable in synchronism with the fixing belt to permit the heating member to heat the fixing belt and to press the pressurizing mechanism against the support member via the fixing belt and the recording material.
According to a fourth aspect of the present invention, there is provided a method for forming an image, comprising:
developing a latent image to form a first developing agent image on a first image carrier by using a first developing agent;
forming a second developing agent image on a second image carrier by using a second developing agent;
transferring the second developing agent image onto a recording surface of a recording material after transfer of the first developing agent image onto the recording surface of the recording material; and
fixing the transferred image to the recording surface by introducing a recording material having the transferred image into a fixing device including a fixing belt movably supported by a rotatable heating member and a rotatable support member equipped with a surface elastic layer having a hardness not higher than 40xc2x0, and a pressurizing mechanism arranged to face the support member with the fixing belt interposed therebetween and equipped with a pressurizing member movable in synchronism with the fixing belt to permit the heating member to heat the fixing belt and to press the pressurizing mechanism against the support member via the fixing belt and the recording material.
Further, according to a fifth aspect of the present invention, there is provided a fixing device, comprising:
a fixing belt movably supported by a rotatable heating member and a rotatable support member equipped with a surface elastic layer having a hardness not higher than 40xc2x0; and
a pressurizing mechanism arranged to face the support member with the fixing belt interposed therebetween and equipped with a pressurizing member movable in synchronism with the fixing belt.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.